In recent years, light-emitting diodes (LEDs) have replaced neon as the dominant illumination method for channel-letter

signage. Specific methods and principles need to be followed, however, to generate optimal results.
近年来，发光二极管（LED）已经取代霓虹灯成为槽型发光字标识的主要照明来源。然而，我们仍需要遵循具体的方法和原则来使LED发光字产生最佳的照明效果。

The following are some techniques that can assist in generating peak performance for LED-illuminated channel letters. Some

apply to both front- and reverse-lit types of letters, while others are more particular to one than the other.
以下是一些能够帮助LED照明发光字发挥最佳性能的技术。有些技术均可适用于前置照明发光字和背光照明发光字，而有些技术则更适合其中一类。

Front-lit letters
前置照明发光字

The colour of the acrylic face is an important variable in producing optimal illumination for a front-lit channel letter. Somecolours will produce better results than others.
亚克力材料表面的颜色是影响前置照明发光字最佳照明性能发挥的重要因素。有些颜色会比其他颜色产生更好的发光效果。

Red, for example, is usually an excellent option for an illuminated sign face. The human eye contains a higher concentration ofred photoreceptor cells (i.e. cones) than those for other colours. This is one of the reasons red achieves a high degree ofnighttime visibility for channel letters.
例如，红色通常是照明标识表面材料颜色的最佳选择。因为人眼含有比其他颜色更高浓度的红色感光细胞（即视锥细胞），这是红光槽型发光字在夜间实现高可见度的原因之一。

Another face colour with strong visibility characteristics for illuminated signs is white, which presents a clear nighttimeappearance in part because it reflects all of the colours in the light spectrum. This is why government departments oftransportation specify white letters on a green background for highway signs.
另一种使照明标识能够拥有强烈可见度的表面材料为白色，它在夜间也能够呈现出清晰的外观，其原因是白色能够反射光谱中所有的颜色。这就是为什么政府交通部门在公路标识的绿色背景上指定使用白色发光字的原因。

There are certain other acrylic face colours, however, that can prove problematic and may not present an optimal appearance atnight, regardless of the configuration of the LEDs lighting them, because they tend to absorb—rather than emit—much of theillumination. These include dark blue and dark green.
也有一些其他的亚克力材料表面的颜色不太适合作为发光字表面材料的颜色，并且无法在夜间呈现出标识明亮的照明外观。无论LED光源的配置如何，拥有这些颜色的表面材料更倾向于吸收（而不是散发）大部分的光源，其中就包括深蓝色和深绿色。

When clients specify such colours for their channel letter faces, signmakers should inform them about the potential drawbacksin terms of appearance, before their orders are submitted.
但是当你的客户指定此类颜色作为发光字表面材料的颜色时，标识制作者应该在完成订单任务之前告知客户有关于他们的标识产品外观方面可能存在的缺陷。

With dark blue, by way of example, the eye tends to focus on it slightly in front of—rather than directly on—the retina,causing a ‘halo’ effect to appear around the lighting. This effect can make the illuminated letters difficult to read undercertain circumstances.
举例来说，当人们在注视深蓝色的时候更倾向于将视觉焦点放在眼前（而不是直接聚焦在视网膜上），从而容易在光源附近产生“光晕”效应，这种效应会使发光字难以阅读。

Burgundy, which is typically specified as a vinyl rather than acrylic face colour, can also prove problematic. It is importantto note, however, these guidelines only refer to darker shades of these colours and do not mean the lighter shades of the sameshould not be used. Indeed, light green can present a fine image for a sign.
深紫色通常是乙烯基材料的表面颜色而不是亚克力材料的表面颜色，而这种颜色也是非常难以辨认的。但需要注意的是，这些限制标准仅针对此类颜色的深色分类，并不意味着其浅色分类是不可以使用的。事实上，浅绿色可以为照明标识提供良好的图像显示效果。

Return depth
反射深度

Another factor affecting illumination performance for front-lit LED channel letters is the return depth.
影响前置照明LED发光字照明性能的另一个因素是反射深度。

The current standard return depth for front-lit channel letters is 127 mm (5 in.), which will generally provide an excellentperformance for letters that are populated with the appropriate number of LED modules. That said, a 76-mm (3-in.) return depthis also becoming increasingly common today.
前置照明发光字的当前标准反射深度为127毫米（5英寸），只要发光字填充了数量合适的LED模组，那么它们通常就可以发挥出优越的性能表现。与此同时，现在76毫米（3英寸）的反射深度也变得越来越普遍。

（图1）

The latter configuration offers a few potential advantages in terms of illumination. First, the shorter distance the light musttravel from the LED to the face material leads to an overall brighter appearance. Secondly, the shorter return depth reduces ‘ricochet lighting,’ i.e. illumination that bounces off the sides of the letter before reaching the acrylic face (see Figure1).
后者配置在照明方面拥有一些潜在的优点。首先，LED光源到表面材料的距离越短，标识的总体亮度就越高。其次，较短的反射深度减少了“跳动照明”，即在到达亚克力材料表面之前从发光字内部的两侧弹起的折射光线（参见图1）。

So, while a standard return depth can provide perfectly acceptable performance, the shorter return may result in better LED-based illumination for front-lit channel letters.
因此，虽然标准的反射深度可以提供标识完美的性能呈现，但较短的反射深度可能会提高前置照明LED发光字的亮度。

Stroke width
行程宽度

The stroke width of channel letters is another factor that will affect the performance of LED illumination. (In this context,‘stroke’ refers to single line or component of the letter, such as the vertical segment of a capital letter ‘T.’)
槽型发光字的行程宽度是会影响LED照明性能的另一个因素。（在这种情况下，‘行程’是指单行或发光字的组成部分，例如大写字母‘T’的垂直部分。）

Periodically, a sign shop’s clients will submit designs for their channel letters with a stroke width of less than 38 mm (1.5in.). This can cause issues and reduce the performance of LED-based illumination, as a stroke that small does not allow for thecorrect placement of the modules.

通常一家标识商店的客户将需要为他们的发光字提供设计方案，当发光字的行程宽度小于38毫米（1.5英寸）时。就很容易出现问题并且降低以LED模组为照明基础的发光字的照明性能，因为行程太短，从而无法正确地放置模组。

Hence, a good rule of thumb is for all letter strokes to be at least 38 mm wide. And if the customer’s design has specified asmaller stroke, the signmaker should ask if that specification can be altered accordingly, prior to production.
因此，丰富的经验告诉我们几乎所有发光字的行程宽度至少应该为38毫米。如果客户提交的设计方案中呈现的行程宽度较短，那么标识制造商应该在生产之前询问是否可以相应地更改规格。

Number of strands
股数

Another important variable in achieving optimal illumination is the number or concentration of LED strands mounted inside thechannel letter. If an insufficient number is used, it can result in a poor appearance.
实现最佳照明的另一个重要因素是安装在发光字内部的LED灯束的数量或密集程度。如果使用的LED灯束不足，那么将很难呈现一个优质的照明外观。

（图2）

One factor in determining the necessary number of strands is the viewing angle range for each LED module. This range is definedas the area covered by the module’s cone of light before losing 50 per cent of its brightness (see Figure 2).
确定所需灯束数量的一个因素是每个LED模组的视角范围。这个范围被定义为在模组光锥损失50％的亮度之前所覆盖的区域（见图2）。

Such ranges vary between different brands of LEDs, but typically, each interior span of 127 mm (5 in.) requires its own LEDmodule strand. The precise implementation of this common practice will depend on the specific module’s viewing angles.
不同品牌的LED之间其范围有所不同，但通常情况下，每个内部跨度为127毫米（5英寸）的发光字都需要适合自己的LED模组灯束。这种常见做法的具体实施将取决于具体模组的可视角度。

Return interior paint
内部反光涂料

Another factor that assists in achieving optimum LED illumination performance is the channel letter’s interior paint orcoating.
另一个有助于实现LED最佳照明性能的因素是发光字的内部涂料或涂层。

Highly reflective paint will both enhance the brightness of the illumination and reduce the probability of ‘hot

spots,’ i.e. where certain sections of a front-lit letter’s face appear brighter than others.
高反光涂料既能提高照明亮度，又能降低“光斑”的可能性，“光斑”即前置照明发光字表面的某些部分比其他部分显得更亮。

In comparison, letters where the return’s interior is unfinished will exhibit reduced illumination performance. This guidelineapplies both front- and reverse-lit channel letters.
相比之下，内部未完全覆盖反光涂料的发光字将表现出低质量的照明性能。本条说明均适用于前置照明和背光照明的发光字系统。

Reverse-lit letters
背光照明发光字

For reverse-lit channel letters, the primary challenge for LED illumination is to produce a halo of sufficient brightness andbreadth to provide a complete and legible outline for each of the letters.
对于背光照明发光字而言，对于其LED照明的主要挑战是发光字要产生足够亮度和宽度的光晕，为每个发光字提供完整清晰的轮廓。

It has become a common practice to mount the LED modules to the back of channel letters, rather than to the front of theirinterior face. In this scenario, the modules are mounted directly onto a clear, thermoformable, impact-resistant polycarbonatesheet that forms the back of each letter. The LEDs’ light is directed toward the inside of the light, but then reflected backout. When configured correctly, this setup can provide an even, balanced halo of light around the letter, as viewed from thefront.
将LED模组安装到槽型发光字的背面而不是前置照明发光字的内部已经成为常见做法。在这种情况下，模组直接安装在发光字背面的清晰的可热成型抗冲击聚碳酸酯板上。此时，LED的光线直接照射发光字的内部，然后再进行反射。当发光字得到正确的安装时，人们从发光字的前面看就可以看到发光字周围均匀而平衡的光晕。

Mounting distance
安装距离

The proper appearance of reverse-lit channel letters depends in part on the capability of the reflected light of the LEDs tofan out from behind to create the halo effect. This capability will vary depending on the letters’ mounting distance from thesupporting building’s wall or façade (see Figure 3).
背光照明发光字的实际外观呈现，在一定程度上取决于LED发出的光线在经过反射后，在背景墙上呈扇形散开而产生的光晕效应的能力。这种能力取决于发光字与支撑建筑物的墙壁或立面之间的安装距离（见图3）。

（图3）

The typical mounting distance for halo-lit channel letters is between 38 and 51 mm (1.5 and 2 in.) from the wall. If theletters are mounted any closer than that minimum distance, then the halo may be compromised and appear too small, making thesign more difficult to read at night.
标准发光字光晕照明的安装距离是，发光字与墙面的距离为38至51毫米（1.5至2英寸）。如果发光字距离墙面的安装距离比规定的最小距离更近，那么光晕可能会受到影响并且显得非常小，使得标识在夜间更难被发现。

Return depth
反射深度

Just as with front-lit letters, the return depth of reverse-lit letters will affect the appearance of their halo illumination.
就像前置照明发光字一样，背光照明发光字的反射深度也会影响其光晕照明的外观。

Generally, a 76-mm return is specified, to provide the optimal degree of reflected light. A 127-mm return may not allow for asufficiently bright halo.
一般来说，76毫米的反射深度可以提供最佳的反射光照明效果。而127毫米的反射深度则可能会降低光晕的照明质量。

Façade characteristics
建筑物的墙面特征

The characteristics of the mounting surface and location must also be taken into account when planning the installation ofreverse-lit channel letters with LEDs, as they can have a substantial effect on the presentation of a sign’s haloillumination.
在计划安装带有LED的背光照明发光字时，还必须考虑安装表面和位置的特性，因为它们可能会对标识照明光晕的显示产生实质性影响。

Phenolic wall panels, for example, which are sometimes applied to the exteriors of buildings, have a reflective quality thatmay negatively affect the appearance of a sign. Their shiny surface can either amplify or distort the halo lighting, to thepoint where it appears misshapen.
例如，有时应用于建筑物外部的酚醛墙板可能会对标识外观产生负面的影响。因为这种墙板的光泽表面可以放大或扭曲标识的照明光晕，甚至使标识的光晕外观出现畸形。

Another issue with mounting a reverse-lit letter set onto a reflective surface is the actual LED modules themselves can becomevisible within the halo’s reflection on the façade. This becomes more of a concern in situations where the letters are mounted at a lower elevation, closer to the people viewing them.
在反光表面上安装背光照明发光字的另一个问题是实际的LED模组本身将可以在外观的光晕反射中变得可见。当标识安装的高度较低，人们更容易近距离地观察标识时，模组本身的可见性就会更高。

A façade that has been painted in a substantially different colour from that of the halo lighting may also affect the sign’s appearance, to varying degrees. A bright yellow wall surface, for example, can make white halo lighting appear yellowish, which may not be what the client wants.
如果墙面上涂有大面积的与发光字产生的照明光晕不一样的颜色，也会影响标识的外观。例如，一个明亮的黄色墙面可能会使发光字的白色光晕呈现淡黄色，那么这可能就不是客户想要的了。

Such potential issues should be discussed with the customer prior to the installation of the sign, so as to avoid the element of surprise and to prevent the customer’s displeasure with the letters’ final appearance.
这些潜在的问题应该在安装标识之前与客户进行讨论，以避免意外因素的产生，并避免客户对发光字的最终外观不满。

Backer panels
背光面板

Another technique for optimizing LED-based illumination for reverse-lit letters is to add a backer panel.
优化背光照明LED发光字的另一种技术是添加背光面板。

A backer panel is basically a contoured aluminum sheet that is specified in a chosen colour and then mounted behind a channel letter set. It may be used with either front- or reverse-lit channel letters, but will only affect the illuminated appearance of the latter.
背光面板主要是一个柔性铝板，它可以由制作者自主确定颜色，然后安装在发光字标识的后面。它可以用于前置或背光的槽型发光字标识，但只会影响到后者的照明外观。

There are compelling advantages to adding a backer panel for reverse-lit channel letters. First, the panel’s colour can be chosen to blend in with the building façade’s colour, making the difference inconspicuous during the day. Secondly, a backer panel provides an even and neutral surface for the halo illumination.
为背光照明发光字添加背光面板将使发光字具有非常显著的优势。首先，背光板的颜色可以选择与建筑墙面的颜色相吻合，使面板与墙面在白天的差异并不是特别明显。其次，背光面板为光晕照明提供了一个均匀和中性的表面。

Overall, a backer panel provides an ideal surface for halo illumination with LEDs. It avoids the problems with colour, texture and reflection that can otherwise result from mounting reverse-lit letters directly to a building’s façade.
总体而言，背光面板为LED光晕照明提供了理想的表面。它避免了由于将背光发光字直接安装到建筑物的外墙而导致的颜色、纹理和光线反射等方面的问题。

Finding the proper configuration
选择合适的配置

LEDs can provide an effective and economical source of illumination for channel-letter signs, but taking full advantage of their capabilities requires the letter set to be properly configured in the first place, in terms of face colour, return depth and numerous other variables. Incorrect choices with regard to any of these variables can compromise the performance and appearance of the illuminated letters after they have been installed.
LED可以为槽型发光字标识提供经济且有效的照明源，但要充分利用其功能，需要首先对发光字组件进行适当配置。就表面颜色、反射深度和众多其他变量而言，这些变量中的任何一个的错误选择都可能会对安装后的照明发光字的性能和外观造成影响。